1. Field of the Invention
The invention relates to a vehicle that is provided with a continuously variable transmission device and, more particularly, to a hybrid vehicle that is provided with a continuously variable transmission device.
2. Description of Related Art
Japanese Patent Application Publication No. 2002-243031 (JP 2002-243031 A) discloses a shift control device for an automatic transmission. The control device obtains a shift target value from an operational point that is determined by a throttle opening and a vehicle speed, and executes continuously variable gear ratio control for controlling an automatic transmission gear ratio.
Techniques for determining whether to perform fixed gear ratio control or optimum fuel efficiency control depending on whether a control throttle opening is equal to or higher than a predetermined threshold have been studied for a vehicle that is provided with a continuously variable transmission (hereinafter, also referred to as a “continuously variable transmission device”).
Also, techniques for controlling a vehicle having a plurality of modes, such as a power mode and an eco mode, present for a relationship between the amount of an accelerator operation by a driver and a control throttle opening and allowing mode switch by the driver have been known.
A vehicle in which these controls are executed in combination is studied. The mode switch by the driver causes the relationship between the accelerator operation amount and the control throttle opening to be switched. Then, the control throttle opening is changed across a predetermined threshold by the mode switching operation, even if the amount of the accelerator operation by the driver is not changed. In this case, control switching may occur between the fixed gear ratio control and the optimum fuel efficiency control.
In this case, an engine rotation speed may fluctuate and the driver may feel a sense of discomfort if the control switching occurs between the fixed gear ratio control and the optimum fuel efficiency control in a state where the engine rotation speed of the fixed gear ratio control and the engine rotation speed of the optimum fuel efficiency control deviate from each other.